1. Field of the Invention
The present invention relates to a fuel supply apparatus, which supplies fuel in an internal combustion engine.
2. Description of Related Art
Nowadays, various on-vehicle electric devices are installed in a vehicle. In order to improve a fuel consumption of an internal combustion engine of the vehicle, it is necessary to minimize the electric power consumption of these on-vehicle electric devices.
As an exemplary way of reducing the electric power consumption of such an on-vehicle electric device, there is known a controller, which is provided in a fuel supply control apparatus and controls an electric power supplied to an electric fuel pump that pumps fuel from a fuel tank to the internal combustion engine (see, for example, Japanese Patent No. 3794879B2 or Japanese Patent No. 4178354B2).
The controller strictly controls the electric power supplied to the fuel pump based on a required quantity of fuel, which is required by the internal combustion engine. In this way, a discharge quantity of fuel, which is discharged from the fuel pump, is controlled based on the required quantity of fuel, which is required by the internal combustion engine, thereby enabling a reduction in the electric power consumption of the fuel pump.
Japanese Patent No. 3794879B2 and Japanese Patent No. 4178354B2 teach an intank fuel supply apparatus, which includes the fuel pump placed in the inside of the fuel tank. The fuel supply apparatus includes the fuel pump and a cover member made of a resin material. The fuel pump is placed in the fuel tank as discussed above, and the cover member covers a hole, i.e., an opening of the fuel tank and supports the fuel pump. The controller is installed to the cover member.
When the controller is operated, the controller generates heat. Therefore, it is required to effectively release the heat generated at the controller. In the fuel supply apparatus of Japanese Patent No. 3794879B2, the cover member includes a casing, which receives the controller, and a heat releasing plate, which conducts the heat generated at the controller to a metal fuel pipe. The heat releasing plate is embedded in the cover member.
In the fuel supply apparatus of Japanese Patent No. 4178354B2, the cover member includes a casing, which receives the controller, and a cover, which closes an opening of the casing and radiates the heat generated from the controller. The cover is fixed to the casing with fixing means (e.g., screws) through a gasket. The gasket limits intrusion of water and dust into the inside of the casing, in which the controller is received.
In the fuel supply apparatus of Japanese Patent No. 3794879B2, the casing, which receives the controller, is formed in the cover member, and a resin cover plate is installed to the casing to close the opening of the casing. As discussed above, in the cover member, the casing has the opening, which opens upwardly, so that the cover plate, which protects the controller received in the casing, needs to be provided separately from the heat releasing member.
In the fuel supply apparatus of Japanese Patent No. 4178354B2, the heat releasing cover, which covers the opening of the casing, has an effective heat releasing capability. However, it is required to clamp the gasket between the casing and the heat releasing cover, and the fixing means is required to fix the heat releasing cover to the casing.
The cover member further includes an outside connector and an inside connector. The outside connector electrically connects between an external device and the controller. The external device may be an internal combustion engine controller, which is located at an outside of the fuel tank and outputs a command signal according to a required amount of fuel, which is required by the internal combustion engine. The outside connector includes a connector housing and electrically conductive line members. Specifically, the connector housing is formed integrally with the cover member that is made of the resin material. One end part of each conductive line member is exposed externally from the connector housing of the outside connector, and the other end part of the conductive line member is electrically connected to a corresponding terminal of the controller.
The inside connector electrically connects between the fuel pump and the controller. Similar to the outside connector, the inside connector includes a connector housing and electrically conductive line members. Specifically, the connector housing is formed integrally with the cover member that is made of the resin material. One end part of each conductive line member is exposed externally from the connector housing of the inside connector, and the other end part of the conductive line member is electrically connected to a corresponding terminal of the controller. The conductive line members of the outside connector and the conductive line members of the inside connector are embedded in the cover member.
When the controller is operated, heat is generated. The heat, which is generated at the controller, is conducted to the terminals of the controller and the resin material of the cover member located around the controller. Thereby, each of the terminals, the conductive line members and the resin material will be expanded by the heat depending on a thermal expansion coefficient thereof.
In general, the thermal expansion coefficient of the resin material is different from the thermal expansion coefficient of the electrically conductive metal material. Therefore, even when the resin material and the electrically conductive metal material are exposed to the same heat, an amount of thermal expansion of the resin material differs from an amount of thermal expansion of the electrically conductive metal material. Thus, when the cover member, the terminals and the conductive line members are thermally expanded, a stress is concentrated at a connecting portion between the terminal of the controller and the corresponding conductive line member. Depending on the amount of stress concentrated at the connecting portion, the electrical connection state between the terminal and the conductive line member may be deteriorated to cause a disconnection between the terminal and the conductive line member.
Also, when a gap is formed between, for example, the cover member and the conductive line members due to a difference in the expansion coefficient between the resin material of the cover member and the electrically conductive metal material of the conductive line members, water or moisture may possibly be conducted to the conductive line members and causes short circuiting between the electrically conductive line members. Also, in this state, when the electric voltage is applied to the conductive line members, galvanic corrosion may occur at the conductive line members, thereby deteriorating a reliability of the fuel supply apparatus.